The line was electrified in 1913 and has belonged to the Chemins de fer du Jura (CJ) since 1944.

[2] The 9 km-long line connected Tramelan with Tavannes, which lay on the existing standard-gauge Sonceboz-Sombeval–Moutier railway opened on 1874.

A very high level of performance was required for the steam locomotives as the line had gradients of up to 4.0 percent.

The reason for the electrification was the opening of the meter-gauge, electrically operated Tramelan-Breuleux-Noirmont Railway (TBN).

The electric supply to the catenary of the two lines was carried out through a substation in Tramelan, which was equipped with backup batteries.

[4] Advances in electrical engineering enabled the continuation of the narrow gauge line from Tramelan through the heights to Les Breuleux and Le Noirmont to connect to the Saignelégier–La Chaux-de-Fonds railway (SC) (French: Chemin de fer Saignelégier–La Chaux-de-Fonds).

On 1 January 1927, the two electrically operated railways TT and TBN, which previously formed a joint venture, joined to form the Tavannes–Le Noirmont Railway [fr] (French: Chemin de fer Tavannes – Le Noirmont).

With the merger of the four railway companies in the then Bernese Jura, the foundation was laid for a comprehensive technical renovation.

The converter plant in Tramelan was replaced by three rectifiers in Orange, Les Reussilles and Le Noirmont.

[10] Scheduled steam trains are operated by La Traction on the Pré-Petitjean–Saignelégier–Le Noirmont–Tavannes route from July to September.

[11] A depot in Tramelan, where the workshop for all CJ vehicles is located, is used to maintain rolling stock used in regular traffic.

[10] Transports Régionaux Neuchâtelois (TRN) rolling stock is also regularly maintained at the local underfloor lathe.

After Tramelan station, the line climbs at 5.0 percent on a winding route to the hamlet of Les Reussilles where the Franches-Montagnes plateau starts.

Afterwards, the line passes through several meadows and fields to cross the high moor and "La grande Tourbière" nature reserve.